A database of databases for Common Era paleoclimate applications

We present a merged database of five curated databases (DoD2k version 2.0.0) developed for Common Era (1–2000 A.D.) paleoclimate research. A toolkit to create the database is also provided and leverages codebases developed by individual database developers and the paleoclimate data informatics communities over the past decade. It includes Python notebooks for (1) loading each database from its public repository, using a common, compact set of terms for metadata and data management; (2) their merger using that common set of dictionary terms; (3) a multistage algorithm to identify candidate duplicates; (4) an operator-supervised, semiautomated decisionmaking procedure, checking against a common set of metadata and comparison metrics; and (5) creation and checking of the finalized, duplicate-free database across 22 dictionary terms. Each of the curated databases, which arise from individual, community and PAGES (Past Global Changes) 2k working groups, represent a range of development approaches, from single archive, single observation datasets with a range of reported environmental responses, to multiarchive-multiobservation collections which target a specific climate response. The resulting DoD2k spans 13 archive types, 37 data types, and 4781 records within the Common Era. We illustrate the value of the DoD2k with two applications. In the first, we extract the moisture (M) and temperature (T) sensitive subset of records and perform an empirical orthogonal function (EOF) analysis on the resulting multi-archive, multi-observation MT-sensitive dataset. In the second, we show that calcite speleothem oxygen isotopic composition is consistent with that simulated using simple models of this proxy system. DoD2k may also be useful for paleoclimatic detection and attribution analysis using proxy system modeling, data assimilation, and deep learning for the development and testing of improved proxy system models. The database can be accessed at https://doi.org/10.25921/sptp-g618 (Evans et al., 2025). The toolkit can be accessed at https://doi.org/10.5281/zenodo.15676255 (Luecke et al., 2026).